1. Field of the Invention
The present invention relates to an empty-can treatment system and method for removing coating layers from surfaces of empty cans each formed from a steel material and an aluminum material and for separating the steel material and the aluminum material from each other for recycling.
2. Description of the Related Art
Conventionally, a can formed from a steel material and an aluminum material has been used to contain a soft drink or the like. Such a can is generally configured such that a bottom wall and a peripheral side wall are formed from a steel material and a lid wall is formed from an aluminum material. Also, coating is applied to the surface of the peripheral sidewall. Used empty cans are recycled to new material in waste disposal and treatment facilities. In this case, a steel material and an aluminum material are separated from each other so as to be recycled separately (as disclosed in, for example, Japanese Patent No. 3284398). In the disclosed recycling process, empty cans are heated by use of a heating means, and subsequently a granulator separates a steel material and an aluminum material.
When the above-mentioned empty cans are to be recycled, a coating layer formed on the surface of each empty can must be burned away at high temperature through application of heat. However, when the empty cans each formed from a steel material and an aluminum material (used to form a lid wall) are heated at high temperature, the aluminum material is excessively oxidized, leading to a decreased recovery rate for the aluminum material.